System for exchanging heat within an environment using an axial-flow heat exchanging structure with spiral-finned tubing

ABSTRACT

An axial-flow heat exchanging structure having a proximal end and a distal end for exchanging heat between a source of fluid at a first temperature and the environment (e.g. ground, water, slurry) at a second temperature. The axial-flow heat exchanging structure comprises a thermally-conductive flowguide tube having a hollow conduit extending from said proximal end to said distal end. A spiral-finned tubing is disposed within the hollow conduit of said thermally-conductive flowguide tube, and has a central conduit for conducting a heat exchanging fluid, from said proximal end, along the central conduit towards the distal end, and returning back to the proximal end along a spiral annular flow channel formed between the thermally-conductive flowguide tube and the spiral-finned tubing.

RELATED CASES

This Application is a Continuation of the U.S. application Ser. No.11/076,428 filed Mar. 9, 2005; said Application being assigned to andcommonly owned by Kelix Heat Transfer Systems, LLC of Tulsa, Okla.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a novel method of and apparatus fortransferring heat using heat exchanging fluids that are safely isolatedfrom the environment above and below the Earth's surface and circulatedwithin a sealed heat exchanging structure so as to improve the heattransfer performance of aqueous-based fluid heat transfer systems,wherein the ground, a lake, a river, or sea water is used as the primaryor secondary heat sink or heat source in the sealed heat exchangingstructure.

2. Brief Description of the State of Knowledge in the Art

The development of refrigeration processes, associated equipment andtwo-phase chemical refrigerants evolved primarily from the need ofmankind to preserve food. Several different kinds of heat transfersystems have been developed for dissipating heat removed from the foodto the exterior of the food storage container.

One kind heat transfer system is a typical refrigeration system whichincludes an evaporator for absorbing heat from one location, a condenserfor dissipating heat to another location, a compressor for compressingthe vaporous two-phase refrigerant exiting the evaporator for deliveryinto the condenser where the refrigerant is condensed back into aliquid, and a two-phase throttling device connected to the evaporatorinlet for receiving the liquid refrigerant and refrigerant expansion, tocomplete a refrigeration cycle.

Condensers can be constructed in various configurations, namely: as atube with air-cooled fins, or as a water-cooled tube and shellconfiguration. In the water-cooled tube and shell condenser, the rate ofheat transfer between the refrigeration-sealed system refrigerant andthe water flowing around the tube and shell condenser tube is muchhigher than the rate of heat transfer between the refrigeration-sealedsystem refrigerant and air flowing around the tubes of the air-cooledfin and tube condenser.

A water-cooled tube and shell condenser is normally connected with pipesto a cooling tower and a water pump. The heat is absorbed by the waterwhile circulated through the condenser. The heat in the water enteringthe cooling tower is then dissipated into the atmosphere from the watercompleting a closed-loop water-cooled refrigeration process.

Environmental concerns have caused strict restrictions to be placed onwater-cooled tube and shell condenser systems utilizing a water pump togather water from other sources such as a lake, a river, sea water, andother fluid systems to be circulated through the water-cooled tube andshell condenser of heat transfer systems. Environmental contaminationsvary but are mostly related to chemical concentrations and temperaturevariations being dispensed into the water source.

A water-cooled tube and shell condenser can be connected with pipes to aground-source heat transfer well which is used to dissipate heat intothe Earth. In various manufacturing processes, the required operatingtemperature and capacity or volume of heat transfer fluid circulatedthrough the ground source heat transfer well, may not require addingrefrigeration to the system.

Residential and commercial comfort air conditioning systems usingair-cooled condensers are well known in the art and are used extensivelyworld-wide on air conditioners including heat pumps. Water-cooled tubeand shell condensers are normally used in large tonnage commercial andindustrial applications such as high-rise buildings, natural gasdehydration, and liquefied natural gas gasification systems.

A heat pump, originally called reverse refrigeration, reverses therefrigeration process through the use of sealed system valves andcontrols causing the evaporator to dissipate heat while causing thecondenser to absorb heat. In its cooling mode of operation, a heat-pumpair conditioning system will dissipate heat into the Earth while, andabsorb heat from the Earth in its heating mode of operation.

Over the years, ground/water source heat pump has proven very useful asa very efficient form of heating and cooling technology. The use ofground/water source type heat pumps have three distinct advantages overair source type heat pumps, namely: during the peak cooling and heatingseasons, the ground/water source usually has a more favorabletemperature difference than the atmospheric air; the liquid-refrigerantexchanger on the heat pump permits a closer temperature approach than anair-refrigerant exchanger; and there is no concern withfrost/snow/ice/dirt buildup or removal on the heat exchanger.

In general, prior art heat pump installations have employed undersizedground loops because refrigerant-based fluids can provide a sufficienttemperature difference between the fluid and the ground so that enoughheat is transferred to and from the ground to match the heating/coolingload on the heat pump; however, the use of undersized ground loops isalso known to reduce the SEER rating of the heat-pump system. Also, thedesign goals of prior art heat pump systems have been to minimize thelength of the metal pipe used in the ground loop, while just passing theminimum standards for efficiency.

When prior art heat pump systems experience peaks or spikes inheating/cooling load during daily operation, thermal storage solutionsare oftentimes added to the system to average the load over the timeperiod of interest. Thermal storage solution also help reduce the costof the ground loop by allowing the loop to be sized for the average baseload over the day, week or season. In fact, many large buildings andresidences use thermal storage solutions in order to reduce the cost ofheating and cooling by (i) using less expensive night-time electricalloads to heat/cool the thermal mass, and then (ii) using the thermalmass to heat/cool the building during the day. In order to reducecapital cost of the heat pump system, prior art heat pump systeminstallations often use the metal rebar in the foundation or piling as amajor part of the thermal mass of the ground loop of the heat pumpsystem.

Ground source or water source type heat pumps can use a close or openloop as a heat exchanger. Open loops include water circulated to coolingtowers; water circulated between wells, geothermal steam wells, watercirculated in a body of water such as a river or lake. Closed loopsinclude aqueous based fluids and refrigerant based fluids circulated incooling/heating coils that transfer heat to air, water, and ground. Mostpower plants use at least one open loop to generate steam (the burnerexhaust) and one open loop (cooling towers or lake) to condense thesteam back to water. The de-ionized steam source water is preserved in aclose loop to prevent scale buildup in the heat exchanger. Mostconventional refrigerators, freezers and air conditioners use a closedloop of refrigerant to cool the load and an open loop of external air tocondense the refrigerant.

The shortcomings and drawbacks of using air to transfer heat from thecondenser coil is that air requires a high temperature differential anda large condenser coil surface area to get reasonable heat transferrates. The high temperature differentials translate to a high-pressuredifferential which implies higher energy costs to transfer a unit ofheat. When a heat pump uses a liquid, from a water or ground loop, totransfer heat from the condenser coil, a smaller coil and a lowertemperature and pressure differential can be used to transfer the sameunit of heat as the air cool condenser coil which, in turn, improvesefficiency and reduces energy costs.

When closed loops are used in the ground or water source of a heat pumpsystem, there is a trade off between using (i) metal tubing with a highheat transfer coefficient (i.e. which is subject to corrosion andthermal expansion), and (ii) plastic tubing with a low heat transfercoefficient (which is resistant to corrosion and thermal expansion). Foraverage soil conditions, plastic tubing usually will require 3 times theheat transfer area of the metal tubing to maintain an equivalent heattransfer rate. Metal tubing is usually reserved for refrigerant basedfluids due to the high fill pressures and the reactivity of therefrigerant with plastic tubing.

While protective coatings and grouting can reduce the corrosion rates ofmetal tubing, pin holes in the coating or grout can actually concentratethe anode corrosion rate in the pin-hole area. Electrical measurementshave shown that circulating aqueous based fluids between the ground loopand heat pump can cause the flow of a low level current between thebuilding and the ground.

In accordance with convention, a close-loop ground/water source heatpump can use a refrigerant based fluid or an aqueous based fluid. Withrefrigerant based fluids, the heat pump can use a high differentialtemperature to transfer heat between the ground and the fluid in thetubing, but extra energy load reduces the SEER rating of the heat pumpsystem. Metal tubing is used to contain the pressurized refrigerantbased fluid and minimize the volume of refrigerant in the ground loopsystem due to the high heat transfer coefficient of the metal. Asdiscussed in U.S. Pat. No. 5,025,634 to Dressler, refrigerant basedfluids have very high maintenance cost when a small leak develops in theground/water loop and a very high environmental impact when there is arelease of the refrigerant. Also, over a long period of time, fieldexperience has shown that high pressure head loss can develop in theclosed ground/water source loop when lubricating oil from the compressorcollects low spots in horizontal loop or at the bottom of the bore holein vertical loop. The inventors design goal was to use an aqueous basedfluid in the ground loop to overcome the environmental risk andmaintenance problems with refrigerant based fluids.

With most aqueous-based fluid ground/water source loops, the heat pumpuses a small close-loop refrigerant heat exchanger to transfer heat toor from the aqueous fluid. The small heat exchanger reduces the capitalcost of the heat pump and reduces the chances of refrigerant releases tothe environment. In areas with ground movement, such as earthquakeszones, subsidence bowls, and deep freeze/thaw zones, the boreholethermally-conductive flowguide tube and transfer piping can developleaks due to repeated damage over time as discussed in U.S. Pat. No.4,993,483 to Kurolwa. The inventors design goal was to use a judiciouschoice of components in the aqueous base fluid; so that, theenvironmental impact of a large leak can be reduced to non-hazardousspill and the impact of a small leak would be reduced to addition ofmake up fluid to the loop.

Ground loop installations vary from trenched horizontal loops tomultiple bore holes. As disclosed in U.S. Pat. No. 4,644,750 to Lockettand Thurston and in U.S. Pat. No. 4,325,228 to Wolf, a horizontal groundloop's performance is affected by fluctuation in atmospheric surfacetemperature and soil moisture content, whereas, the ground loop based onmultiple bore holes has a stable fluid temperature and heat transfercoefficient for both heating and cooling thermal loads. For heat andcooling loads located on small land surfaces or arid land, the groundloop heat exchanger based on multiple bore holes can provide a heat pumpwith a stable heat sink or source as described in U.S. Pat. No.4,392,531 to Ippolito.

The first major improvements to ground loop fluid heat transfer usingmetal tubing and refrigerant based fluids were disclosed in U.S. Pat.No. 5,816,314 to Wiggs et. al, U.S. Pat. No. 5,623,986 to Wiggs, U.S.Pat. No. 5,461,876 to Dressler, U.S. Pat. No. 4,867,229 to Mogensen, andU.S. Pat. No. 4,741,388 by Kurolwa where metal tubing was bent into ahelix shape to increase heat transfer between the refrigerant and theground. The five patents show that the ‘vertical spiral heat exchanger’or the ‘bore-hole spiral heat exchanger’ provides the heat pump with astable heat sink or source for heating and cooling. The shortcoming ofthese designs is the increased capital cost of spiral bending of thetubing and the increased installation cost of trying to run spiral benttubing in a deviated well.

Another popular technique used in prior art heat pumps involvesinsulating the metal, fluid-return tube from the bottom of the bore holeso to prevent heat transfer from incoming fluid, which significantlyimproves the heat exchanger performance. The deficiency of prior artinsulating methods has caused a significant increase in installationcosts and a significant increase in capital cost associated withinsulating materials. Notably, as the return line was far enough awayfrom the loop to not cause any significant thermal interference,insulating the fluid return tube was not required for earlier horizontalground loop heat exchangers.

U.S. Pat. No. 4,741,388 to Kurolwa discloses using a spirally-corrugatedouter tube to create the spiral flow shape for increased heat transferof the fluid, which is similar to the spiral channeled tubes used in asteam boiler.

U.S. Pat. No. 5,623,986 to Wiggs discloses that external spirally shapefins can be used to drill short vertical heat exchangers into sand-loamsoils or mud bottoms, but field experience has shown that there is tomuch fin damage for hard rock/ground surface.

U.S. Pat. No. 5,937,665 to Kiessel et al., discloses other improvementsto refrigerant based groundloops, wherein an air heat exchanger is usedto the system to reduce the load on the ground loop.

U.S. Pat. No. 6,138,744 by Coffee discloses using a large storage tankof water to a horizontal ground loop that is continuously replenished byan external water source such as water well. This technique involvescombining an open water loop and a lose ground loop.

U.S. Pat. No. 6,615,601 by Wiggs discloses combining a solar heatingloop and a water evaporative cooling loop to the ground loop so as tosupplement the heating and cooling load.

U.S. Pat. No. 6,212,896 to Genung discloses a ground loop with largewell bores to make room for a vertical thermal siphon to enhance theheat transfer in the large well bore. The short coming of this idea isthat the heat is transfer to the thermally-conductive flowguide tubewall with a laminar flow of fluid.

U.S. Pat. No. 6,672,371 to Amerman et al. created a ground loop bydrilling multiple well bores from one pad and using plastic U-tubes forthe heat exchanger. By using many plastic U-tubes with low heat transferin series, an equivalent metal heat exchanger performance can beachieved in the ground loop.

U.S. Pat. No. 6,789,608 to Wiggs discloses a technique for extending theperformance of the U-tube heat exchanger by installing an insulatingplate between the tubes to make two close separate half wells withminimal thermal interference between each well.

Thus, while various advances have been made in heat pump system designand implementation, there is still a great need in the art for animproved method of and apparatus for transferring heat from above orbelow the Earth's surface using a sealed fluid circulation system whichmay or may not incorporate the use of a refrigeration system, whileovercoming the shortcomings and drawbacks of prior art methodologies andequipment.

SUMMARY AND OBJECTS OF THE PRESENT INVENTION

Accordingly, it is a primary object of the present invention to providea method of and apparatus for transferring heat from above or below theEarths surface using a sealed fluid circulation system employed aspiral-like heat transfer structure, while overcoming the shortcomingsand drawbacks of prior art methodologies.

Another object of the present invention is to provide an axial-flow heatexchanging structure having a proximal end and a distal end forexchanging heat between a source of fluid at a first temperature and theenvironment (e.g. ground, water, slurry) at a second temperature.

Another object of the present invention is to provide such an axial-flowheat exchanging structure which comprises an outer thermally-conductiveflowguide tube having a hollow conduit extending from said proximal endand distal end, and spiral-finned tube disposed within the hollowconduit of the outer thermally-conductive flowguide tube, and has acentral conduit for conducting a heat exchanging fluid, from theproximal end, along the central conduct towards the distal end, andreturning back to the proximal end along a spiral annular flow channelformed between the thermally-conductive flowguide tube and thespiral-finned tube.

Another object of the present invention is to provide such an axial-flowheat exchanging structure which further comprises an insulating centertube disposed within the central conduit, for conducting the heatexchanging fluid from the proximal end, along the central conducttowards the distal end, and returning back to the proximal end along thespiral annular flow channel.

Another object of the present invention is to provide such an axial-flowheat exchanging structure which further comprises a cap installed on theproximal end and having fluid inlet and outlet ports (e.g. a fluidmanifold) for injecting the heat exchanging fluid into the axial-flowheat exchanging structure at a third temperature, and withdrawing theheat exchanging fluid out of the axial-flow heat exchanging structure ata fourth temperature.

Another object of the present invention is to provide such an axial-flowheat exchanging structure which can be used for sinking heat into theground during cooling operations, or sourcing heat from the groundduring heating operations.

Another object of the present invention is to provide a heat pump systememploying the axial-flow heat exchanging structure of the presentinvention, wherein the heat transfer performance of aqueous based fluidheat transfer is substantially improved, and wherein the ground, a lake,a river, or sea water can be used as the primary or secondary heat sinkor heat source.

Another object of the present invention is to provide such a heat pumpsystem which may or may not incorporate the use of a refrigerationsubsystem.

Another object of the present invention is to provide such a heat pumpsystem, wherein the heat transfer performance of aqueous based fluids issubstantially improved by using heat-pump heating/cooling heatexchangers where the ground is used as the primary or secondary heatsink/source in a closed loop.

Another object of the present invention is to provide such a heat pumpsystem, wherein capital/installation cost of the total heat pump systemis substantially reduced.

Another object of the present invention is to provide a heat pump systememploying an axial-flow heat exchanging structure which is installedinto the earth, a lake, a river, sea water or other heat sink or heatsource to absorb heat or dissipate heat into or from the heat transferfluid by isolating the heat transfer fluid entering the centerinsulating tube, from the helically flowing fluid exiting the assembly.The interior surface of the well thermally-conductive flowguide tube isthe primary heat transfer surface of the axial flow heat exchangerassembly.

Another object of the present invention is to provide an axial-flow heatexchanging structure that cab be used in diverse kinds of heat pumpsystems, wherein the axial-flow heat exchanging structure can bemanufactured as a primary system, a system sub-component, or asub-component kit.

Another object of the present invention is to provide a axial-flow heatexchanging structure for ruse in a heat pump system, wherein the heatexchanging surface area of the structure is increased by fluting theplastic surface of the outer thermally-conductive flowguide tube and byincreasing the length of the bore into the ground (bore length) as aresult of drilling deviated-type wells in aquifer zones of the Earth.

Another object of the present invention is to provide a axial-flow heatexchanging structure for ruse in a heat pump system, wherein as the heattransfer surface area and the contact volume of the ground/water sourceloop increase, the circulating fluid temperature will approach theaverage ground temperature through out the full duration of the heatingand cooling seasons.

Another object of the present invention is to provide a heat pumpsystem, wherein a uniform bore hole is drilled into an aquifer zone anda smooth metal pipe or a fluted plastic pipe is installed within thebore hole so that the axial-flow heat exchanging structure of thepresent invention can be installed in most geologic ground types withoutmajor changes in installation procedures.

Another object of the present invention is to provide a method of andapparatus for enhancing the heat transfer in aqueous based fluidground/water source loop systems so that a low differential temperature,high mass-rate heat pump can be used to cool or heat a thermal load froma building or industrial process.

Another object of the present invention is to provide a ground/watersource heat-pump system that has a SEER rating that exceeds air-sourceheat pump systems and ground-source heat-pump systems using arefrigerant based heat-transfer fluid.

Another object of the present invention is to provide an improved heatpump system, wherein the aqueous based fluid contains a biodegradableanti-freeze and dye to minimize the environmental impact of leaks in theground loop and improve leak detection in the ground loop multi-wellgrid.

Another object of the present invention is to provide an improved heatpump system, wherein for small leaks, make up fluid is injected into thesystem to maintain system pressure and prevent vapor locking thecirculation pump, and for large leaks, the system is systematicallychecked with a mass flow meter and an ultrasonic leak detector toidentify the location of the leak.

Another object of the present invention is to provide apparatus formanufacturing the spiral-finned tubing employed within the axial-flowheat transfer (exchanging) structure of the present invention.

These and other objects of the present invention will become apparenthereinafter and in the Claims to Invention.

BRIEF DESCRIPTION OF DRAWINGS

For a more complete understanding of how to practice the Objects of thePresent Invention, the following Detailed Description of theIllustrative Embodiments can be read in conjunction with theaccompanying Drawings, briefly described below, in which visualdescriptions are provided showing the installation of the presentinvention in the ground, water, or mud line environments.

FIG. 1 shows the axial-flow heat exchanging structure of the presentinvention shown installed in a deviated well bore with smooth metalthermally-conductive flowguide tube, wherein the deviated well bore isdrilled nearly horizontal in the aquifer zone to maximize heat transferto the ground, wherein the deviated well bore uses a short turningradius to deviate from vertical to near horizontal and the metalthermally-conductive flowguide tube is grouted to surface to preventaquifer contamination.

FIG. 2 shows a natural gas dehydration system using a heat pump systemof the present invention shown in FIG. 1, with a deviated well drilledin an aquifer for the ground loop, wherein the natural gas and otherliquids are produced from the well that is completed in the gas zone.

FIGS. 3 and 4 show the front and back views of a section of singlespiral or helical finned tubing used to create an annular spiral orhelical flow channel within the axial heat exchanging structure of thepresent invention, for the aqueous based heat exchanger fluid, andwherein this small-diameter, spiral finned tubing can be deliveredrolled on a large spool to install in the thermally-conductive flowguidetube, the tubing is cut to size and the well cap is fused on as shown inFIG. 48.

FIGS. 5 and 10 show the front and top views of a double spiral/helicalfin set used to create spiral or helical flow in large borethermally-conductive flowguide tube.

FIGS. 6 and 7 show the front and top views of a single spiral-finnedtubing with the insulated inner tube installed in thethermally-conductive flowguide tube shown in FIG. 1, wherein the gas gapbetween the central insulated inner tube and the spiral-finned outertube provides insulation, and the gap distance between the walls remainsuniform due to the 3 standoffs on the inner insulation tube.

FIGS. 8 and 9 show the front and top views of the single-spiral finnedtubing without the inner insulation tube installed, and wherein the finscan be extruded with the tubing for small diameters or extruded over ajoint of larger diameter tubing, and wherein for diameters exceeding 18inches or 0.5 meters, the fins can be rolled from flat stock and weldedon the tubing joint.

FIGS. 11 and 12 show the front and top view of the insulated innertubing, wherein the standoffs provide the gas gap needed for insulationbetween the inner insulation tube and outer spiral-finned tube, whereinthe fill gas can be argon, nitrogen, or even ethane, however argon is abetter insulation gas and is readily available in the field.

FIGS. 13, 14 and 15 show the front, bottom and cross-section views ofinsulated spiral-finned tubing joint with collar for large diameterspiral finned tubing that cannot be rolled on spool.

FIGS. 16, 17, and 18 show the front, bottom and cross-section views ofthe spiral-finned tubing with collar without the inner insulated tubeinstalled.

FIGS. 19, 20, and 21 show the front, bottom and cross-section views ofthe insulated inner sleeve that is fusion welded on both ends inside thespiral-finned tubing to provide the gas gap, wherein high pressure argonor other gas can be used to fill the gas gap before the fusion process,and wherein the inner insulation tube can be made of high density,foamed plastic to reduce heat transfer and friction pressure drop.

FIGS. 22 and 23 show the front views of tubing joints with a singlespiral fin and a double spiral fin.

FIGS. 24 and 25 show the front and top views of the spiral-finned tubingshoe that is fusion welded to the bottom of the spiral-finned tubing soas to protect the spiral fins during the installation process.

FIGS. 26, 27 and 28 show the front, bottom and cross-section views ofthe smooth thermally-conductive flowguide tube that is grouted in theearth, wherein the smooth thermally-conductive flowguide tube is usuallymetal due to its high heat transfer coefficient, wherein the threadedcollars are used to attach the joints together.

FIGS. 29, 30 and 31 show the front, bottom and cross-section views ofthe fluted thermally-conductive flowguide tube that is grouted in theearth, wherein the flutes on the plastic thermally-conductive flowguidetube give it additional surface area to counteract the low heat transfercoefficient of the plastic, wherein the flutes also give the plasticthermally-conductive flowguide tube additional strength.

FIGS. 32 and 33 show the forward and reverse flow patterns in smooththermally-conductive flowguide tube with single spiral finned tube,wherein during the cooling season, pumping down the annulus gives thebest approximation to a cross flow heat exchanger for liquid-gasmixtures where the liquid adsorbs the gas phase when the pressureincreases as the mixture is pump down the thermally-conductive flowguidetube annulus.

FIG. 34 shows the forward flow pattern for a double spiral finned tube,wherein the multiple spiral fins are used for large diameterthermally-conductive flowguide tube, wherein for large diameters, thespiral finned tubing joints can be pre-installed in thethermally-conductive flowguide tube joints for shipment.

FIGS. 35 and 36 show front and top views of fluted thermally-conductiveflowguide tube with single spiral flow tubing installed, wherein thatthe pitch of the spiral and the fluted thermally-conductive flowguidetube should be practically close for maintaining the spiral flow patternin the channel.

FIGS. 37 and 38 show the spiral flow pattern of fluid as it is pumpeddown the annulus and up the annulus of the axial-flow heat exchangingstructure of the illustrative embodiment of the present invention.

FIGS. 39, 40, 41 and 42 show cross-sectional views of the tangentialflow directions for the fluted control volume shape of the axial-flowheat exchanging structure of the illustrative embodiment of the presentinvention, wherein a square-like shape control volume of the axial-flowheat exchanging structure usually has one vortex for flow rates ofinterest, wherein a rectangle-like shaped control volume of theaxial-flow heat exchanging structure with an aspect ratio near 2 to 1usually has two vortexes for flow rates of interest, and wherein forrectangle-like shapes with an aspect ratio greater than 4 to 1, therecan be vortex near each fin with a laminar slot flow region in thecenter of the control volume.

FIGS. 43, 44, 45 and 46 show cross-sectional views of the tangentialflow directions for a smooth rectangular control volume shape of theaxial-flow heat exchanging structure of the illustrative embodiment ofthe present invention, wherein a square-like shape control volume of theaxial-flow heat exchanging structure usually has one vortex for flowrates of interest, wherein a rectangle-like shaped control volume withan aspect ratio near 2 to 1 usually has two vortexes for flow rates ofinterest, and wherein for rectangle-like shapes with an aspect ratiogreater than 4 to 1, there can be a vortex near each fin with a laminarslot flow region in the center of the control volume.

FIG. 47 shows the spiral-finned tubing in a corrugatedthermally-conductive flowguide tube of the axial-flow heat exchangingstructure of the illustrative embodiment of the present invention.

FIG. 48 shows an axial-flow heat exchanging structure of the presentinvention installed with a well cap, wherein the well cap holds thespiral-finned tubing off the bottom of the thermally-conductiveflowguide tube so as to prevent buckling of the plastic spiral-finnedtubing and seals the thermally-conductive flowguide tube annulus fromfluid leaks.

FIG. 49 shows fluid distribution around the spiral annulus of theaxial-flow heat exchanging structure shown in FIG. 50, as well as aroundits well cap, that is, for fluid being pumped down the spiral annulus ofthe axial-flow heat exchanging structure.

FIGS. 50 and 51 show the cross-section and top views of wellthermally-conductive flowguide tube and well cap installed in theaxial-flow heat exchanging structure of the present invention, whereinthe fluid return and injection manifold have been removed for drawingclarity, and the well cap can have manifold of several small holes for alow friction pressure drop or a single medium size hole for a littlehigher friction pressure drop.

FIGS. 52, 53, and 54 show a compression ring well cap and clamped wellcap installed in the axial-flow heat exchanging structure of the presentinvention, wherein either well cap has an O-ring or U-ring seal aroundthe well thermally-conductive flowguide tube to prevent fluid leaks,wherein the clamps on the thermally-conductive flowguide tube to preventfluid pressure from pumping well cap off the thermally-conductiveflowguide tube for shallow spiral tubing depths or high fluid pressures,and wherein for permanent installations in cement structures, the wellcap is fusion welded, as shown in FIG. 52, so as to reduce the risk ofleaks.

FIGS. 55, 56, 57 and 58 show three different styles of annulus fluidreturn for the spiral-finned tubing employed within the axial-flow heatexchanging structure of the present invention, wherein the first styleuses a connected manifold of small holes or one medium size hole drilledin the well cap with fluid exiting parallel or perpendicular tothermally-conductive flowguide tube axis, wherein the second style usestube fittings welded/fused to the side of the thermally-conductiveflowguide tube for fluid injection and return (for use in concretepiling or pier installations), wherein the third style uses a tubefitting welded to the side of the thermally-conductive flowguide tubefor annular fluid return (for use in foundation installations when thetube fittings are compression), and wherein all the designs have a lowfriction pressure drop.

FIG. 59 shows a close up of the well cap and the insulated spiral flowtubing employed within the axial-flow heat exchanging structure of thepresent invention, and wherein the drawing shows the transition frominternal insulation to external insulation used in the horizontal runbetween wells or heat pump.

FIG. 60 shows the axial-flow heat exchanging structure of the presentinvention installed in a deviated well bore, wherein the horizontalsection of the structure is drilled into an aquifer zone and thevertical section thereof connects the horizontal section back to thesurface.

FIG. 61 shows the axial-flow heat exchanging structure of the presentinvention installed in a near horizontally bored well in the side of amountain, mesa, or hill, wherein the well bore path is deviated tofollow an aquifer zone if available at the site, and wherein forbuildings with a deep basement or built on the side of a hill, thedeviated well bores are drilled in the wall of the basement.

FIG. 62 shows the axial-flow heat exchanging structure of the presentinvention installed in a well bore that is cap below the surface toprevent significant heat transfer to the ground/water surface oratmosphere, and wherein for areas that have significant ice orfreeze/thaw movement, the distribution pipes should be protected againstdamage and, if possible, the well should be capped below the frost line.

FIGS. 63, 64, and 65 show the axial-flow heat exchanging structure ofthe present invention installed vertically or horizontally infoundations or pilings of a building, bridge, or other structure.

FIGS. 66, 67 and 68 show the axial-flow heat exchanging structure of thepresent invention suspended in an aqueous solution or mud, wherein thevertical metal fins are used to increase the heat transfer area of thethermally-conductive flowguide tube by making an external thermo-siphonfor aqueous solution circulation.

FIG. 69 shows the axial-flow heat exchanging structure of the presentinvention installed in a bridge component or piling, wherein inearthquake areas, the pilings are wrapped in a metal sheath to preventstructural damage in the earthquake, and the sheath could be installedwith spiral-like flow channels to provide ground/water source heat toprevent icing of the road way or sidewalks during the winter.

FIGS. 70 and 71 show the application of pad drilling of nine deviatedwells to minimize the ground surface impact while maximizing the volumeof ground contacted by the well bores, wherein long term operationallows the ground loop to thermal bank heat from the cooling season foruse in the winter season, for cooling loads only, a shallow horizontalloop can be added to the ground-loop to remove heat from the thermalbank during the winter season, in the limit of deviated well drilling, ahorizontal well as shown in FIG. 60 could replace the pad of ninedeviated wells, the pad drilling also has the advantage of reduced heatloss from horizontal gathering piping and reduced risk of accidentaldamage from contractor digging operations.

FIGS. 72 and 73 show the application of a single well heat exchanger fora residential home and multiple pad drilled heat exchangers for largercommercial heat and cooling loads, wherein an optional thermal bank tankis provided for night time operation when the electrical energy cost arecheaper or for day time operation when solar cells can provideelectrical energy.

FIGS. 74 and 75 show the installation of small and large axial-flow heatexchanging structures of the present invention in ground to preventicing or snow accumulation on side walks, bridges and heavily traveledintersections or steeply pitched roads.

FIGS. 76 and 77 show applications using sea water or ballast water asthe heat-pump heat sink for gas dehydration and oil de-waxing, whereinaxial-flow heat exchanging structure of the present invention installedin is used to extract heat from the gas to cause the temperature to dropwhich then condenses water vapor and/or light hydrocarbon vapors.

FIG. 78 shows the application of the axial-flow heat exchangingstructure of the present invention in a ground-loop heat exchangingsystem used for pipeline quality gas dehydration on shore for gasproduced from remote off shore wells.

FIGS. 79, 80 and 81 show the axial-flow heat exchanging structure of thepresent invention installed in a ground-loop heat exchanger used for gasdehydration and condensate separation on land for a single well or agathering system, wherein as shown in FIG. 80, the gas in the liquidseparator is cooled to a temperature near the aquifer temperature, andthen gas is cooled with a heat pump to a temperature near the gashydrate temperature using a rotating heat exchanger, wherein the glycolcycle or calcium chloride salt cycle is used to remove moisture from thegas-hydrate temperature to the −30 F. dew point for pipeline sales, andwherein the system reduces energy cost of gas dehydration and eliminatesthe release of benzene, toluene and other carcinogenetic hydrocarbonvapors to the atmosphere.

FIGS. 82 and 83 show the axial-flow heat exchanging structure of thepresent invention installed in a seawater heat exchanging system aboarda submarine for centralized and decentralized air condition andequipment cooling, wherein the purpose of the system is to reduce noisegeneration and increase the safety in case of a hull breach.

FIGS. 84, 85 and 86 show both side and cross-section views of theaxial-flow heat exchangers of the present invention used in a submarineapplication, wherein the outer tubes are made of metal and they arefinned to provide maximum heat transfer.

FIGS. 87, 88 and 89 show a side and cross-sectional views of theaxial-flow heat exchanging structure of the present invention installedin an aqueous-based fluid to air heat exchanger.

FIG. 90 shows the application of a single well heat exchanger for aresidential home and multiple pad drilled heat exchangers for largercommercial heat and cooling loads, and wherein an optional thermal banktank is provided for night time operation when the electrical energycost are cheaper or for day time operation when solar cells can provideelectrical energy.

FIG. 91 shows system of eleven deviated wells connected together in aheat pumping network.

FIG. 92 is a front view of a rotating extrusion die used to manufacturethe spiral-finned tubing within the axial-flow heat exchanging structureof the present invention, wherein the die is fabricated from a materialcompatible with the material being extruded and with a melting pointtemperature above that of the material being extruded.

FIG. 93 is a right side view of the rotatable extrusion die showing howthe center mold core is held in position by support arms.

FIG. 94 is a front view of a rotatable extrusion die with the opening toform the first flow guide and an additional flow guide opening.

FIG. 95 is a right side view of the rotatable extrusion die illustratinghow the distance between the surface of the mold core determines thedesired wall thickness of the flow guide tube as it is extruded throughthe rotatable extrusion die.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

Referring to FIGS. 1 through 91, the various illustrative embodiments ofthe axial-flow heat exchanging structure of the present invention willbe now described in detail.

As shown in FIG. 1, a horizontal/deviated well is drilled into anaquifer for installation of the ground loop heat exchanger of thepresent invention, which is referred to herein as “an axial-flow heatexchanging structure”. As will be described in greater detailhereinafter, the axial-flow heat exchanging structure has a proximal endand a distal end for exchanging heat between a source of fluid at afirst temperature and the environment (e.g. ground, water, slurry) at asecond temperature. The axial-flow heat exchanging structure comprisesan outer thermally-conductive flowguide tube having a hollow conduitextending from the proximal end and distal end, and spiral-finned tubedisposed within the hollow conduit of the outer thermally-conductiveflowguide tube, and has a central conduit for conducting a heatexchanging fluid, from the proximal end, along the central conducttowards the distal end, and returning back to the proximal end along aspiral annular flow channel formed between the thermally-conductiveflowguide tube and the spiral-finned tube. The axial-flow heatexchanging structure may also comprise an insulating center tubedisposed within the central conduit, for conducting the heat exchangingfluid from the proximal end, along the central conduct towards thedistal end, and returning back to the proximal end along the spiralannular flow channel.

A cap is installed on the proximal end and is provided with fluid inletand outlet ports to facilitate (i) the injection of the heat exchangingfluid into the axial-flow heat exchanging structure at a thirdtemperature, and (ii) the withdrawal of the heat exchanging fluid out ofthe axial-flow heat exchanging structure at a fourth temperature. Theaxial-flow heat exchanging structure of the present invention can beused a component within a heat pump system to substantially improve theheat transfer performance of aqueous based fluid heat transfer therein,wherein the ground, a lake, a river, or sea water can be used as theprimary or secondary heat sink or heat source. Heat pump systemsemploying the axial-flow heat exchanging structure of the presentinvention may or may not incorporate the use of a refrigerationsubsystem.

As shown in FIG. 1, the deviated well bore, with the axial-flow heatexchanging structure installed therein, is used as a heat exchanger withthe aquifer in the ground. The well is drilled with a short radius turn(less than 50 ft. radius) into the middle of the aquifer zone. The metalthermally-conductive flowguide tube (component of the axial-flow heatexchanging structure) is cemented with sanded grout to surface toprevent aquifer contamination and increase the heat transfer coefficientto the ground. After cementing operations, the thermally-conductiveflowguide tube is cleaned with a mild acid solution with surfactant toremove mud, mill scale and grout tailings. The spiral pitch and numberof fins on the spiral-finned tubing component are selected to rotate thefluid at the desired heat-pump circulation rate. Once these parametershave been determined, the spiral-finned (insulated) tubing is run to thebottom of the flowguide tube shoe and sealed off at thethermally-conductive flowguide tube cap with fusion welding. The arrayof wells can be connected to the gathering lines (using insulatedplastic surface piping) for series or parallel operation with theheat-pump heat exchanger formed by an arrangement of installedaxial-flow heat exchanging structures. Finally, the ground loop isfilled with an aqueous heat transfer fluid and the air is bled out ofthe high spots in the system to achieve optimum performance. By usingthe axial-flow heat exchanging structure of the present invention, thisdeviated well design reduces installation cost and material cost.

As shown in FIG. 1, the design goal for the ground/water source loop ofthe heat pump system of the illustrative embodiment of the presentinvention has been to provide enough heat-transfer surface area andground/water volume to insure the circulating fluid temperature of theground/water source loop does not go above/below the average groundtemperature by 7° F. or 3° C., under continuous load during peak of theheating/cooling season. By maintaining a return fluid temperature within7° F. or 3° C. of the ground/water source temperature, the SEER ratingof the heat pump system will be maximized for the whole heating/coolingseason. A commercial objective of the design has been to use acombination of metal and plastic tubing to increase heat transferto/from the ground while reducing the life-time cost of the ground loopwhich includes the capital, maintenance and operational cost averagedover the life-time of the system.

If the time averaged thermal seasonal heat and cooling loads are nearlyequivalent, then the core volume of the ground loop can be designed tostore heat during the cooling season and, subsequently, the heat can beextracted from the core volume during the heating season. If the timeaveraged thermal load is mostly heating or cooling, then ground loop isdesigned to transfer heat without significant storage in the groundvolume.

For small spikes over base load, larger well bore diameter or the ironmass in the foundation can be used for thermal storage to average outthe operational temperature of the fluid. With a spiral fin design andthe slot aspect ratio ranging from a 1 to 1 square to a 1 to 2.5rectangle, tubing diameters can exceed 36 inches or 1 meter withoutsignificantly reducing heat transfer coefficient to the ground/watersource. For large spikes over base load, a larger tank volume is addedto the ground loop for additional thermal storage.

For an estimated yearly thermal load, a thermal simulator can be used todetermine the number wells used in the ground loop array, the amount ofthermal storage needed to average out the daily peak loads and theamount of core volume needed in the array to store heat from the coolingseason to use in the heating season. For large thermal projects, thesimulator can be used to optimize capital cost of drilling (horizontalwell bore length versus number of wells in array), material cost of thethermally-conductive flowguide tube (thermally-conductive flowguide tubediameter versus metal or plastic), the approach temperature of theground loop and refrigerant used by the heat-pump system. However, theactual heat transfer rate and time coefficient of the ground-loop arrayof wells should be determined with a transient temperature test of theground loop and the actual heat storage of the ground loop should bedetermined with a complete year of history of circulating fluidtemperature and load.

The well design parameters such as grout thickness, thermally-conductiveflowguide tube material, spiral pitch, number of spiral fins, insulatedwall thickness of inner tube, and fluid composition can be optimizedusing analytical equations for steady state operation. Most of the wellarray design parameters such as well depth, well length, well spacingshould be optimized for the given aquifer properties with a thermalsimulator over a multi-year load to account for the thermal storage ofearth and the seasonal transients. Most of thermal storage parametersfor the insulated volume of fluid in a tank or in the array of wellbores, or the insulated volume of concrete in the foundation can beempirically fit with simple equations so that the peak loads can beaveraged over the daily operation of the heat pump. The design goal isto install a ground loop with thermal storage so that it can transferthe daily thermal load from the heat pump for the minimum capital costand operational cost.

FIG. 2 shows a natural gas dehydration system using a heat pump systemof the present invention as shown in FIG. 1, with a deviated welldrilled in an aquifer for the ground loop. In this system, the naturalgas and other liquids are produced from the well that is completed inthe gas zone. The natural gas moves through the separator where brackishwater and hydrocarbon liquids are separated form the gas. The naturalgas then moves through the heat pump dehydrator where the temperature isreduced to condense the water vapor and heavier hydrocarbon vapors fromthe natural gas. Finally, the natural gas is then polished with a smallglycol unit to remove the last traces of water vapor for shipment in thenatural gas production supply lines. Notably, in the natural gasdehydration system shown in FIG. 1, the deviated well provides groundloop cooling to dehydrate natural gas in a natural gas productionenvironment. However, for other oil field cooling applications,additional large surface thermally-conductive flowguide tube holes canbe drilled and cemented in the ground for the external metal-pipe,ground-loop heat exchanger. For commercial and residential heating andcooling applications, smaller plastic pipe can be used to make themulti-well ground-loop heat exchanger. Due to the actual drilling costversus heat transfer area, it is better to drill a slanted group ofsmall diameter holes from a pad than to drill one large diameter hole.

For cooling applications, the addition soluble gases to the aqueousbased fluid improve the heat transfer to ground/water source. As thepressure increases with depth of fluid column, the soluble gases areadsorbed by the aqueous fluid; the gases release their stored heat tothe fluid, and in turn raise the temperature of the fluid which in turnincreases the temperature differential between the fluid and theground/water source. Carbon dioxide (CO2) and ammonia (NH3) gases foamedwith surfactants create stable aqueous based fluids used in thisabsorption process. The return line requires insulation to prevent theabsorption of heat as the gases come out of solution as the fluidreturns to the surface. The adsorption and desorption process acts likea low differential temperature refrigerant cycle, but it can be quiteeffective in increasing the heat transfer in the ground/water sourceloop.

For heating applications, the addition of solid particles can increasethe heat capacity of the aqueous based fluid. Micron sized heavy metalor metal oxide particles can be mixed with the aqueous based fluid andsuspended with a shear thinning polymer such as xanthan gum or boratecross-linked polymer. The fluid must be kept in motion or the particleswith eventually settle out and plug the bottom of the well bore.Micron-sized glass spheres containing a low melting point salt can alsobe used to increase the heat capacity of the fluid while maintaining aparticle specific gravity close to 1. Particle specific gravities nearto 1 will prevent settling of the particles in the aqueous fluid, thusallowing a ground loop section to be shut down with out the danger ofplugging the well with settled particles. Field experience has shownthat the composition of the aqueous-based fluid should remain simple toreduce capital cost and that increasing fluid flow rate is a bettersolution to increase heat capacity of the system, except where very highheat transfer rates are required.

Having given an overview of the axial-flow heat exchanging structure ofthe present invention, shown used in a typical heat pump systemapplication, it is appropriate at this juncture to now describe theindividual components of the ground-loop heat pump system in greaterdetail.

As shown in FIGS. 3 and 4, single spiral or helical finned insulatedtubing is used to create an annular spiral or helical flow channelwithin the axial heat exchanging structure of the present invention, forthe aqueous based heat exchanger fluid. As shown, this small-diameter,spiral finned tubing can be delivered rolled on a large spool to installin the thermally-conductive flowguide tube, and the tubing can be cut tosize and the well cap fused on as shown in FIG. 48.

In FIGS. 3 and 4, reference numeral 3B and 4A indicate to the flow guidefor a single helical or spiral fin. The flow guide can be made out ofplastic or metal depending on the static load on the fin. Referencenumerals 3A and 4B indicate the thermally-conductive flow guide tube.The outer wall of the flow guide tube can be made out of metal orplastic depending on the buckling or tensile load of the tubing layingor hanging in the well bore. FIG. 5 shows the front view of doublespiral-finned insulated tubing. 5A points to the insulated flow guidetube. Reference numeral 5B indicates the first flow guide while 5Cpoints to the second flow guide. The number of flow guides used in anyparticular application is determined by the cross-sectional shape of theflow channel and this topic is discussed in detail with reference toFIGS. 39 through 46.

As shown in FIGS. 5 and 10, a double spiral/helical fin set is shownused to create spiral or helical flow in large bore thermally-conductiveflowguide tube. In this design, the friction pressure drop in the groundloop can be reduced, and the number of fin sets can be increased toreduce the flow path length in the well bore. Also, as thethermally-conductive flowguide tube size increases, the number ofhelical fins can be increased to keep the aspect ratio of the flowchannel shape close to 2 to 1 as shown in FIGS. 39 and 43.

As shown in FIGS. 6 and 7, a single spiral-finned tubing with theinsulated inner tube is shown installed in the thermally-conductiveflowguide tube of FIG. 1. In this design, the gas gap between thecentral insulated inner tube and the spiral-finned outer tube providesinsulation, and the gap distance between the walls remains uniform dueto the 3 standoffs on the inner insulation tube. Reference numerals 6Aand 7C indicate the wall thickness of the center tube in spiral-finnedinsulated tubing. The center tube wall thickness is calculated from thematerial strength, from the buckling load of setting the tubing down onthe thermally-conductive flowguide tube shoe and from tensile load ofsupporting the tubing from the thermally-conductive flowguide tube cap.Reference numerals 6B and 7J indicate the center tube flow channel. Thechannel diameter is determined from the amount of thermal storage needin the ground loop or from the friction pressure drop. Reference numeral6C indicates the outer flow guide tube wall thickness which must supportthe tensile load of the tubing and flow guides hanging from thethermally-conductive flowguide tube cap and it must support the shearstress of installing the tubing in the thermally-conductive flowguidetube. Reference numerals 6D and 7B indicate the top side surface of theflow guide. The surface should be smooth to reduce the friction pressuredrop of the flowing fluid. 6E points out the bottom side surface of theflow guide. Reference numerals 6F, 7E, 7F, and 7G indicate the standoffs on the center tube used to create the static or dead gas spacebetween the center tube and the outer flow guide tube. The standoffs canhave a triangular shape for installation at the factory, but fieldexperience shows that the standoffs should have a half cylinder shapefor center tube installation in the field. The number of standoffs usedis determined by the center tube diameter and center tube material.Reference numerals 6G and 7D show the edge of the flow guide. For smallflow guide outside diameters, the edge can be flat, but for largediameters the edge should be radius to prevent flow guide damage byhanging up on an edge in thermally-conductive flowguide tube collar.Reference numerals 6H and 71 indicate the static or dead gas space usedfor insulation between the center tube and the outer flow guide tube.The space could also be filled with a ceramic fiber or ceramic paper.The gas space can be pressurized with an inert, non-condensable gas suchas argon, nitrogen, refrigerant gases, methane, or ethane. The chargegas pressure should be equivalent to half the hydrostatic pressure inthe well bore. Reference numeral 61 indicates the outer flow guide tubeexterior surface. The surface should be smooth to reduce frictionpressure lost and could be curved to promote tangential rotation of thecirculated fluid. Reference numeral 7A indicates the start of the clockwise spiral turn of the flow guide. Reference numeral 7H indicates showsthe interior surface of the outer flow tube. To reduce the heat transferbetween the center tube and outer tube, the surface could be coated witha reflective metal such as aluminum, silver or gold or coated with areflective ceramic powder such as titanium dioxide.

In FIGS. 8 and 9, the single-spiral finned tubing shown in FIGS. 6 and 7is shown without the inner/central insulation tube installed. In thisdesign, the fins can be extruded with the tubing for small diameters orextruded over a joint of larger diameter tubing. For diameters exceeding18 inches or 0.5 meters, the fins can be rolled from flat stock andwelded on the tubing joint. Reference numerals 8A and 9G indicate theinner diameter of the flow guide tube where in the center tube will beassembled. Reference numerals 8B and 8G indicate the beginning and theend of the flow guide tube cut to the desired length to install in thewell bore. Reference numeral 8C indicates the exterior diameter of theflow guide tube. Reference numerals 8D and 9B indicate the top side ofthe flow guide. Not shown in these figures is the fact that both the topand bottom surfaces of the flow guide can be curved to promotetangential rotation of the fluid and to prevent slow flowing areas inthe corners of the spiral flow channel. Reference 8E and 9E show theinterior surface of the flow guide tube. This surface could be coatedwith a reflective metal such as aluminum, silver or gold or coated witha reflective ceramic powder such as titanium dioxide. Reference numerals8F and 9F show the exterior surface of the flow guide tube. This surfaceshould be smooth to reduce the friction pressure of the circulatingfluid. The surface could also be fluted to promote the tangentialrotation of the circulating fluid. Reference numeral 9A indicates thestart of the clock-wise rotation of the spiral flow guide. Referencenumeral 9C indicates the edge of the flow guide. For small flow guideoutside diameters, the edge should be flat to increase the frictionpressure drop of the slot flow so the circulating fluid follows the flowguide instead of trying to bypass it. But for large diameters, the edgeshould be radius with additional thickness to prevent flow guide damageby hanging up on an edge in thermally-conductive flowguide tube collar.Reference numeral 9D indicates the wall thickness of the flow guidetube. The wall thickness is determined by the material used and thecompressive, tensile and shears loads the tubing wall will be exposed toduring installation and operation.

As shown in FIGS. 11 and 12, the standoffs on the insulated inner tubingprovide the gas gap needed for insulation between the inner/centralinsulation tube and outer spiral-finned tube, wherein the fill gas canbe argon, nitrogen, or even ethane, however argon is a better insulationgas and is readily available in the field. In this design, a vacuum isestablished in the field to check for leaks, then the gap is filled withgas to half of the bottom hole pressure. Notably, the standoffs can havea cross-sectional rounded shape instead of the triangular shape, shownin FIG. 12, for easier installation in the field and to prevent damageto the edge during installation in the field.

In FIGS. 13, 14 and 15, insulated spiral-finned tubing is joined with acollar for large diameter spiral finned tubing that cannot be rolled onspool. In this application, the collar can be fusion welded or threadedto the next joint in the field to make a continuous piece of tubing forinstallation in the thermally-conductive flowguide tube. Preferably, theinner tube is fuse welded at the factory on both ends of the outer tubeto provide the seal for the gas gap.

In FIGS. 16, 17, and 18, the spiral-finned tubing is joined with collarwithout the inner insulated tube installed. In this application, thecollar is usually threaded for metal tubing, slip for short lengths ofplastic tubing or even twisted lock with O-ring seal for long lengths ofplastic tubing. Preferably, the wire coil in the collar can be used tofusion weld plastic tubing in the field during installation.

In FIGS. 19, 20, and 21, the insulated inner sleeve is fusion welded onboth ends inside the spiral-finned tubing to provide the gas gap. Inthis application, high pressure argon or other gas can be used to fillthe gas gap before the fusion process. Also, the inner insulation tubecan be made of high density, foamed plastic to reduce heat transfer andfriction pressure drop.

In FIGS. 22 and 23, tubing joints are shown with a single spiral fin anda double spiral fin. The number of helical/spiral fins increases as thediameter of the thermally-conductive flowguide tube increases tomaintain the 1 to 1 or 2 to 1 aspect ratio of the helical flow channel.

In FIGS. 24 and 25, a shoe structure is shown fusion welded to thebottom (distal end) of the spiral-finned tubing so as to protect thespiral fins during the installation process. During this process, theleading edge of the spiral-finned tubing is shown with a radius,however, it can be shaped like a truncated cone. Also while there arefour fins shown, notably however, the number of fins can range from 3 to6, depending on the number of spiral fins used on the tubing.

In FIGS. 26, 27 and 28, the smooth thermally-conductive flowguide tubeis shown from various views. During the installation process, this tubestructure in grouted in the Earth. Preferably, the smooththermally-conductive flowguide tube is usually metal due to its highheat transfer coefficient. Threaded collars are used to attach thejoints together, and the thermally-conductive flowguide tube shoe shownin FIG. 26 usually contains a cement valve and a plug catcher. Smalldiameter tubing is used inside the thermally-conductive flowguide tubeto prevent grout contamination therewithin and to flush the mud out ofthe flowguide tube after grout placement. Such precautions should betaken because hardened grout inside the flowguide tube can damage theplastic spiral edges during insulation and reduce the heat transfercoefficient of the metal wall. To ensure this, a small diameter coiledtubing is run in the annulus of flowguide tube, and grout is pumped tofill the annulus at substantially the same rate as the small diametertubing is pulled to the surface.

In FIGS. 29, 30 and 31, a fluted thermally-conductive flowguide tube isshown. In this design, the flutes on a plastic thermally-conductiveflowguide tube give it additional surface area to counteract the lowheat transfer coefficient of the plastic. The flutes also give theplastic thermally-conductive flowguide tube additional strength. Thethermally-conductive flowguide tube shoe in FIG. 29 usually has a cementvalve and a plug catcher to complete the grouting process. Thethermally-conductive flowguide tube shoe will also have metal forks todig into the wall of the hole to prevent the plasticthermally-conductive flowguide tube from floating when the grout ispumped to surface. An option to prevent the thermally-conductiveflowguide tube from floating off the bottom of the hole is to flash seta small volume of grout in the bottom of the hole to hold thethermally-conductive flowguide tube down while the rest of the grout ispumped to the surface with a small diameter coiled tubing in the annulusof the hole. The small diameter tubing is pulled to the surface atsubstantially the same rate as the grout fills the annulus of the hole.

In FIGS. 32 and 33, the forward and reverse flow patterns are shown insmooth thermally-conductive flowguide tube with single spiral finnedtube. During the cooling season, pumping down the annulus gives the bestapproximation to a cross flow heat exchanger for liquid-gas mixtureswhere the liquid adsorbs the gas phase when the pressure increases asthe mixture is pump down the thermally-conductive flowguide tubeannulus. As the gas phase is absorbed, the fluid temperature increaseswith depth which in turn increases the heat transfer to the ground orwater. During heating season or winter operation, pumping down theannulus with a cold aqueous fluid gives the best approximation to across flow heat exchanger due to the ground temperature increasing withdepth. For horizontal or deviated wells, it is better to pump down theinner tube to maximize heat transfer at the end of the well.

FIG. 34 shows the forward flow pattern for a double spiral finned tube.In this design, the multiple spiral fins are used for large diameterthermally-conductive flowguide tube. For large diameters, the spiralfinned tubing joints can be pre-installed in the thermally-conductiveflowguide tube joints for shipment. O-ring seals are used in the spiralfinned tube collars, so when thermally-conductive flowguide tube jointsare joined together, the O-ring seals the spiral finned tubing also.This helps reduce installation cost and shipping cost for large diameterground loops.

In FIGS. 35 and 36, a fluted thermally-conductive flowguide tube isshown with single spiral flow tubing installed. In this design, thepitch of the spiral and the fluted thermally-conductive flowguide tubeshould be practically close for maintaining the spiral flow pattern inthe channel. The fluid will bypass the fins around the space in theflutes. The whole assembly can be extruded together as atubing-thermally-conductive flowguide tube joint combination, and thejoint combination can be fusion welded in the field with preinstalledwire coils in the collars.

FIGS. 37 and 38 show the spiral flow pattern of fluid as it is pumpeddown the annulus and up the annulus of the axial-flow heat exchangingstructure of the illustrative embodiment of the present invention.Pumping down the annulus for near vertical well bores gives the bestapproximation to a cross flow heat exchanger for ground temperaturesclose the surface. For horizontal or deviated wells in aquifers, it isbetter to pump down the inner insulation tube to maximize the heattransfer at the end of the well.

FIGS. 39, 40, 41 and 42 show cross-sectional views of the tangentialflow directions for an axial-flow heat exchanging structure having afluted control volume shape. An axial-flow heat exchanging structurewith a square-like shape control volume usually has one vortex for flowrates of interest. An axial-flow heat exchanging structure having arectangle-like shaped control volume with an aspect ratio near 2 to 1usually has two vortexes for flow rates of interest. For axial-flow heatexchanging structures having rectangle-like shapes with an aspect ratiogreater than 4 to 1, there can be vortex near each fin with a laminarslot flow region in the center of the control volume. The laminar slotflow region of the axial-flow heat exchanging structure reduces the heattransfer of the fluid with the thermally-conductive flowguide tube walland reduces the efficiency of the spiral flow ground flow loop of theaxial-flow heat exchanging structure of the illustrative embodiment ofthe present invention.

FIGS. 43, 44, 45 and 46 show cross-sectional views of the tangentialflow directions for an axial-flow heat exchanging structure having asmooth rectangular control volume shape. An axial-flow heat exchangingstructure having a square-like shape control volume usually has onevortex for flow rates of interest. An axial-flow heat exchangingstructure having a rectangle-like shaped control volume with an aspectratio near 2 to 1 usually has two vortexes for flow rates of interest.For an axial-flow heat exchanging structure having a rectangle-likecontrol volume shape with an aspect ratio greater than 4 to 1, there canbe a vortex near each fin with a laminar slot flow region in the centerof the control volume. The laminar slot flow region reduces the heattransfer of the fluid with the thermally-conductive flowguide tube walland reduces the efficiency of the spiral flow ground flow loop.

FIG. 47 shows an axial-flow heat exchanging structure having aspiral-finned tubing in a corrugated thermally-conductive flowguidetube. In this design, the corrugated flowguide tube wall increases thesurface area and strength of the thin walled thermally-conductiveflowguide tube. The period of the corrugation flutes is at least onequarter or less of the spiral fin to prevent significant fluid bypassaround the fins. The corrugations will increase the friction pressuredrop in the annulus of the axial-flow heat exchanging structure by afactor of 10% and will increase the heat transfer rate and area thereofby a factor of 40%.

FIG. 48 shows the spiral-finned tubing in the thermally-conductiveflowguide tube of the axial-flow heat exchanging structure installedwith a well cap. The well cap holds the spiral-finned tubing off thebottom of the thermally-conductive flowguide tube so as to preventbuckling of the plastic spiral-finned tubing and seals thethermally-conductive flowguide tube annulus from fluid leaks. In orderto prevent buckling of the plastic spiral tubing, at least ⅔ of thespiral-finned tubing should be hung in tension from the well cap. Usingthe O-ring seal, well cap provides an easy way to remove the spiraltubing in case thermally-conductive flowguide tube fluid leak. The wellcap can be attached to thermally-conductive flowguide tube with threads,with compression bolts or a compression ring.

FIG. 49 shows fluid distribution around the spiral annulus of theaxial-flow heat exchanging structure shown in FIG. 50, as well as aroundits well cap, that is, for fluid being pumped down the spiral annulus ofthe axial-flow heat exchanging structure.

In FIGS. 50 and 51, an axial-flow heat exchanging structure of thepresent invention is shown as having a thermally-conductive flowguidetube and a well cap. In this application, the fluid return and injectionmanifold have been removed for drawing clarity. The well cap can have amanifold of several small holes for a low friction pressure drop or asingle medium size hole for a little higher friction pressure drop. Thesingle medium sized hole is usually threaded for a pipe connection, andthe small holes have an O-ring sealed quick-connect to prevent fluidleaks and reduce the installation time of the pre-made manifold.

FIGS. 52, 53, and 54, axial-flow heat exchanging structures of thepresent invention are shown having either a compression ring well cap ora clamped well cap. In this design, either type of well cap has anO-ring or U-ring seal around the well thermally-conductive flowguidetube so as to prevent fluid leaks. The clamps on thethermally-conductive flowguide tube are provided to prevent fluidpressure from pumping well cap off the thermally-conductive flowguidetube for shallow spiral tubing depths or high fluid pressures. Forpermanent installations in cement structures, the well cap is fusionwelded, as shown in FIG. 52, so as to reduce the risk of leaks.

FIGS. 55, 56, 57 and 58 show three different styles of annulus fluidreturn for the spiral-finned tubing employed within the axial-flow heatexchanging structure of the present invention. In the first style, theaxial-flow heat exchanging structure employs a connected manifold ofsmall holes or one medium size hole drilled in the well cap with fluidexiting parallel or perpendicular to thermally-conductive flowguide tubeaxis. In the second style, the axial-flow heat exchanging structureemploys tube fittings welded/fused to the side of thethermally-conductive flowguide tube for fluid injection and return (foruse in concrete piling or pier installations). In the third style, theaxial-flow heat exchanging structure uses a tube fitting welded to theside of the thermally-conductive flowguide tube for annular fluid return(for use in foundation installations when the tube fittings arecompression). In all three designs, a low friction pressure drop isachieved across the cap of the axial-flow heat exchanging structure.

In FIG. 59, the well cap and the insulated spiral flow tubing employedwithin the axial-flow heat exchanging structure of the presentinvention. This figures shows the transition from internal insulation toexternal insulation used in the horizontal run between wells or heatpump.

FIG. 60 shows the axial-flow heat exchanging structure of the presentinvention installed in a deviated well bore. The horizontal section ofthe structure is drilled into an aquifer zone and the vertical sectionthereof connects the horizontal section back to the surface. This designis used where there is a known water saturated sand, sandstone, orlimestone zone with high water permeability or ground water movement tomaximize heat transfer rate of each well in the ground loop, the warmwater will migrate away from the well bore and create a very slowthermal siphon in the porous formation. This design is used when theground loop will not be used to store heat from the cooling season to beextracted in the heating season. Using this design, one or two wells canbe drilled for retro-fitting an office building or a city block ofresidential houses with ground-loop heat pumps.

FIG. 61 shows the axial-flow heat exchanging structure of the presentinvention installed in a near horizontally bored well in the side of amountain, mesa, or hill. In this application, the well bore path isdeviated to follow an aquifer zone if available at the site. Forbuildings with a deep basement or built on the side of a hill, thedeviated well bores are drilled in the wall of the basement.

FIG. 62 shows the axial-flow heat exchanging structure of the presentinvention installed in a well bore that is cap below the surface toprevent significant heat transfer to the ground/water surface oratmosphere. For areas that have significant ice or freeze/thaw movement,the distribution pipes should be protected against damage and, ifpossible, the well should be capped below the frost line.

FIGS. 63, 64, and 65 show the axial-flow heat exchanging structure ofthe present invention installed vertically or horizontally infoundations or pilings of a building, bridge, or other structure,wherein the heat exchanger can take advantage of the metal rebar used inthe concrete to increase the effective surface area of the outer tube.By installing the ground-loop heat exchanger in the ground or waterbelow the structure, the cement/concrete sheath can perform twofunctions: structural support and heat transfer to the water or ground.If the heating load is small enough and the temperature difference largeenough, then heat exchanger can be used in the thermo-siphon mode usingthe density difference between cold and warm aqueous solution, otherwisea heat-pump is used to increase the heat transfer rate, and as thepiling spacing is very close in building foundations, the whole volumeof ground contained between the pilings can be converted to a thermalbank for peak loads or even to store heat from the cooling season to beused in the heating season. Also, if the top of basement foundation isisolated with insulation, then cement structure and some surroundingground can be converted into a thermal bank for peak load averagingduring winter heating and summer cooling.

FIGS. 66, 67 and 68 show the axial-flow heat exchanging structure of thepresent invention suspended in an aqueous solution or mud. In theseapplications, the vertical metal fins are used to increase the heattransfer area of the thermally-conductive flowguide tube by making anexternal thermo-siphon for aqueous solution circulation. The fin widthto thickness aspect ratio should be less than 10 to 1 to optimize theuse of metal and heat transfer to the aqueous solution or mud. Forinstallations in bodies of water, the fins are coated for anodeoperation to prevent bio-film growth and scaling, which reduces the heattransfer to the aqueous solution.

FIG. 69 shows the axial-flow heat exchanging structure of the presentinvention installed in a bridge component or piling. In earthquakeareas, the pilings are wrapped in a metal sheath to prevent structuraldamage in the earthquake, and the sheath could be installed withspiral-like flow channels to provide ground/water source heat to preventicing of the road way or sidewalks during the winter.

FIGS. 70 and 71 show the application of pad drilling of nine deviatedwells to minimize the ground surface impact while maximizing the volumeof ground contacted by the well bore. In such applications, long termoperation allows the ground loop to thermal bank heat from the coolingseason for use in the winter season. For cooling loads only, a shallowhorizontal loop can be added to the ground-loop to remove heat from thethermal bank during the winter season, in the limit of deviated welldrilling, a horizontal well as shown in FIG. 60 could replace the pad ofnine deviated wells. The pad drilling also has the advantage of reducedheat loss from horizontal gathering piping and reduced risk ofaccidental damage from contractor digging operations.

FIGS. 72 and 73 show the application of a single well heat exchanger fora residential home and multiple pad drilled heat exchangers for largercommercial heat and cooling loads. In this application, an optionalthermal bank tank is provided for nighttime operation when theelectrical energy cost are cheaper or for day time operation when solarcells can provide electrical energy. For remote cooling operations, e.g.for equipment used in cell phone towers, the ground loop can provide auniform operational temperature, wherein for rest area restrooms, solarcells with battery back up can power the heat pump to prevent freezingof the plumbing and provide guest comfort. Also, a long horizontal welldrilled in an aquifer can replace a pad of deviated wells.

FIGS. 74 and 75 show the installation of small and large axial-flow heatexchanging structures of the present invention in ground to preventicing or snow accumulation on side walks, bridges and heavily traveledintersections or steeply pitched roads. In such applications, the groundheat can keep the road surface from icing up and increase theevaporation rate of moisture on the road. Spring and summer operationscan thermally bank (i.e. store) heat for intermittent winter surfacede-icing, and to reduce energy cost, the highway department can remoteoperate the heat pump hours before the bad weather conditions move inthe area and prevent the road conditions from becoming bad.

FIGS. 76 and 77 show applications using seawater or ballast water as theheat-pump heat sink for gas dehydration and oil de-waxing. In suchapplications, the axial-flow heat exchanging structure of the presentinvention can be used to extract heat from the gas to cause thetemperature to drop which then condenses water vapor and/or lighthydrocarbon vapors. The axial-flow heat exchanging structure can also beused to extract heat from oil with a cold finger to cause the wax tobuild up on the cold finger instead of on the pipeline wall transportingthe oil to shore or the heat pump can be used to heat the oil to preventor clean the wax buildup on the pipeline wall. The spiral flow tubingcan be submerged in the open seawater or submerged in the ballast waterin the structure, wherein for open sea water, the exterior of the spiralflow tubing is coated for anode operation to prevent bio-film growth onthe heat exchanger. Using a closed loop heat exchanger with the seawaterin locations teaming with sea life, greatly reduces the maintenance costof the other heat exchangers especially, the heat exchanger used on thepower plant.

FIG. 78 shows the application of the axial-flow heat exchangingstructure of the present invention in a ground-loop heat exchangingsystem used for pipeline quality gas dehydration on shore for gasproduced from remote off shore wells.

FIGS. 79, 80 and 81 show the axial-flow heat exchanging structure of thepresent invention installed in a ground-loop heat exchanger used for gasdehydration and condensate separation on land for a single well or agathering system. As shown in FIG. 80, the gas in the liquid separatoris cooled to a temperature near the aquifer temperature, and then gas iscooled with a heat pump to a temperature near the gas hydratetemperature using a rotating heat exchanger. The glycol cycle or calciumchloride salt cycle is used to remove moisture from the gas-hydratetemperature to the −30 F. dew point for pipeline sales. The system canreduce energy cost of gas dehydration and eliminate the release ofbenzene, toluene and other carcinogenetic hydrocarbon vapors to theatmosphere.

FIGS. 82 and 83 show the axial-flow heat exchanging structure of thepresent invention installed in a seawater heat exchanging system aboarda submarine, for centralized and decentralized air condition andequipment cooling. The purpose of the system is to reduce noisegeneration and increase the safety in case of a hull breach.

FIGS. 84, 85 and 86 show both side and cross-section views of an arrayof axial-flow heat exchangers of the present invention used in asubmarine application. In this application, the outer tubes are made ofmetal and they are finned to provide maximum heat transfer. The finwidth to thickness ratio is less than 10 to 1 to optimize the weight toheat transfer ratio. Also, mixed oxidant is injected into the seawateror a saltwater chlorinator to treat the seawater and prevent bio-filmbuildup on the fins. The heated seawater can be pre-diluted with freshseawater to prevent showing a thermal plume around the submarine.

FIGS. 87, 88 and 89 show a side and cross-sectional views of theaxial-flow heat exchanging structure of the present invention installedin an aqueous-based fluid to air heat exchanger. In this application,the heat exchanger is shown in an ‘A’ frame style. However, it can beused in the conventional block style. In this application, dirtparticles are removed from the air with a filter or electrostaticprecipitator, to prevent fouling the heat exchanger and reduce bio-filmgrowth in the condensate line. Also, an optional ultraviolet light (notshown) can be used to sterilize the air and the surface of heatexchanger, to prevent mold and mildew from growing on the heat exchangerand in the duct work.

FIG. 90 shows the application of a single well heat exchanger for aresidential home and multiple pad drilled heat exchangers for largercommercial heat and cooling loads. In this application, an optionalthermal bank tank is provided for night time operation when theelectrical energy cost are cheaper or for day time operation when solarcells can provide electrical energy for remote cooling operations. Forequipment used in cell phone towers, the ground loop can provide auniform operational temperature. For rest area restrooms, solar cellswith battery back up can power the heat pump to prevent freezing of theplumbing and provide guest comfort. Also, a long horizontal well drilledin an aquifer can replace a pad of deviated wells.

FIG. 91 shows a system of eleven deviated wells connected together in aheat pumping network. This schematic illustrates how the axial-flow heatexchanging structure of the present invention can be combined in variousways to realize improved heat pumps systems capable of handling diversethermal loads.

Referring to FIGS. 92 through 94, apparatus will be described formanufacturing the spiral-finned tubing used within the axial-flow heatexchanging structure of the present invention.

In FIG. 92, a rotating extrusion die is shown for manufacturing thespiral-finned tubing within the axial-flow heat exchanging structure ofthe present invention. Preferably, the die is fabricated from a materialcompatible with the material being extruded and with a melting pointtemperature above that of the material being extruded. The die can beattached to a rotating fixture on the extrusion machinery using boltholes 92H, 921, 92J, and 92K. The rotatable extrusion die can also bewelded to a rotating fixture.

As the liquid material is forced through the extrusion machinery outlet,the rotatable extrusion die 92A can rotate axially in the clockwise orcounter-clockwise direction to form the flow guide through opening 92B.The axial flow heat exchanger flow guide tube and helical shaped flowguide is formed by material passing through opening 92L. The desiredthickness of the flow guide and height of the flow guide from theexternal surface of the flowguide tube are determined by the dimensionsof opening 92B. The inside surface of the flow guide tube is formed bysurface 92N. The external surface of the flow guide tube is formed bysurface 92M. The center mold core 92C is supported and connected to therotatable die by support arms 92D, 92E, 92F, and 92G. The center moldcore can extend beyond the front surface of 92A to support the extrudedmaterial as it exits the rotatable die which is determined by thematerial being extruded.

FIG. 93 shows how the center mold core 93C and 93E are held in positionby support arms 93G, 93H, and 931. The bolt holes 93J, 93K, and 93L canbe drilled through or threaded. The flowguide tube external surface mold93B and 93F shown can be perpendicular to the front surface of FIGS. 92,92A and can be angular. FIG. 94 shows how a rotatable extrusion die withthe opening 94B is used to form the first flow guide and an additionalflow guide opening 94C. Additional flowguide form openings can be cut ormachined into the rotatable extrusion die 94A to form a number of flowguides desired during the extrusion process. FIG. 95 illustrates how thedistance between the surface 95C of the mold core 95B determines thedesired wall thickness of the flow guide tube as it is extruded throughthe rotatable extrusion die.

While various illustrative embodiments of the present invention havebeen disclosed in great detail herein above, is understood that theaxial-flow heat-transfer technology employed in heat pump systems of theillustrative embodiments may be modified in a variety of ways which willbecome readily apparent to those skilled in the art of having thebenefit of the novel teachings disclosed herein. All such modificationsand variations of the illustrative embodiments thereof shall be deemedto be within the scope and spirit of the present invention as defined bythe Claims to Invention appended hereto.

1-22. (canceled)
 23. A heat transfer system for exchanging heat withinan environment, comprising: a source of heat exchanging fluid; and aspiral flow heat exchanging structure of elongated extent installedwithin said environment, and having a proximal end and a distal end, andcapable of exchanging heat between said heat exchanging fluid at a firsttemperature and the environment at a second temperature different thansaid first temperature; wherein said axial-flow heat exchangingstructure includes: thermally-conductive flowguide tubing having ahollow conduit extending from said proximal end to said distal end; andspiral-finned tubing disposed within the hollow conduit of saidthermally-conductive flowguide tubing, and having a central conduit forconducting said heat exchanging fluid, from said proximal end, alongsaid central conduit towards the distal end, and returning back to saidproximal end along a spiral annular flow channel formed between saidthermally-conductive flowguide tubing and said spiral-finned tubing soas to form a loop and exchange heat between said first and secondtemperatures within said environment.
 24. The heat transfer system ofclaim 23, wherein said heat exchanging structure further comprisesinsulating center tubing disposed within said central conduit, forconducting the heat exchanging fluid from said proximal end, along saidcentral conduct towards the distal end with minimal thermal conductionthrough to said spiral-finned tubing, so that the heat exchanging fluidcan exchange heat to said environment by way of saidthermally-conductive flowguide tubing as said heat exchanging fluidflows back to said proximal end along said spiral annular flow channel.25. The heat transfer system of claim 23, wherein said axial-flow heatexchanging structure which further comprises a fluid manifold disposedon said proximal end for injecting said heat exchanging fluid into saidaxial-flow heat exchanging structure at a third temperature, andwithdrawing said heat exchanging fluid out of said axial-flow heatexchanging structure at a fourth temperature.
 26. The heat transfersystem of claim 23, wherein said environment is a region of ground, andsaid axial-flow heat exchanging structure is installed in a well boreformed in said ground.
 27. The heat transfer system of claim 26, whereinsaid well bore is drilled nearly horizontal in an aquifer zone in theground so as to maximize heat transfer to said ground.
 28. The heattransfer system of claim 26, wherein said well bore uses a short turningradius to deviate from vertical to near horizontal and saidthermally-conductive flowguide tubing is grouted to the surface toprevent aquifer contamination.
 29. The heat transfer system of claim 23,wherein the spiral flow of fluid within said axial-flow heat exchangingstructure increases the heat transfer of said heat exchanging fluid withsaid thermally-conductive flowguide tubing by said spiral-finned tubingconstantly rotating the heat exchanging fluid as it flows through thechannel formed between said thermally-conductive flowguide tubing andsaid spiral-finned tubing.
 30. The heat transfer system of claim 23,wherein said fins have a flat edge parallel to said thermally-conductiveflowguide tubing so as to divert the fluid into the channel instead ofaround said fins.
 31. The heat transfer system of claim 23, wherein saidspiral-finned tubing has shoe-structure fused to the bottom of saidspiral-finned tubing so as to prevent fin damage during installation ofsaid spiral-finned tubing within said thermally-conductive flowguidetubing.
 32. The heat transfer system of claim 31, wherein saidthermally-conductive flowguide tubing is constructed by joining togethersections of tubing.
 33. The heat transfer system of claim 31, whereinsaid spiral-finned tubing includes inner insulating tubing to providethermal insulation between said inner insulating tubing, and saidspiral-finned tubing.
 34. The heat transfer system of claim 26, whereinsaid well bores are over-sized to provide a thermal bank around saidthermally-conductive flowguide tubing.
 35. The heat transfer system ofclaim 26, wherein a large tank is buried in said ground near said loopso as to provide a thermal bank during high loading conditions.
 36. Theheat transfer system of claim 26, wherein said environment is theground, and said loop is used to store heat within said environmentduring cooling, and released to said environment during heating.
 37. Theheat transfer system of claim 31, wherein absorbable gases are foamedwith said heat exchanging fluid so as to improve heat transfer whencooling is desired.
 38. The heat transfer system of claim 23, wherein ahorizontal well is drilled into an aquifer, and said axial-flow heatexchanging structure is installed within said horizontal well so as toimprove heat transfer.
 39. The heat transfer system of claim 26, whereina concrete structure buried in the ground is used to make a thermal banksurrounding said loop.
 40. The heat transfer system of claim 26, whereina concrete structure buried in the ground is used to make athermo-siphon to prevent ice buildup on a road, sidewalk, or bridgesurface.
 41. The heat transfer system of claim 23, wherein saidenvironment is a body of open-seawater and said loop is used to cool asubmarine.
 42. The heat transfer system of claim 31, wherein said heatexchanging fluid is passed through a natural gas dehydration unit or anoil de-waxing unit.
 43. The heat transfer system of claim 32, whereinsaid environment is a medium with heat transferring properties, selectedfrom the group consisting of a region of ground, a volume of water, anda volume of slurry.